"This has been the most difficult time in my political life, and in my personal life," Senate President Stanley Rosenberg said Dec. 1, 2017 at a press conference about his husband's actions. Photo: Sam Doran/SHNS

Former Senate President Stanley Rosenberg, who spent more than 27 years in the state Senate and became the first openly gay president of the body, bowed to pressure from his colleagues to resign on Thursday and will leave the Legislature at the end of the week.

Rosenberg's resignation comes on the heels of the release of a damaging report from the Senate Ethics Committee on Wednesday that found Rosenberg failed in his responsibility to protect the Senate from his husband, Bryon Hefner, who he knew to be "volatile" and abusive to staff and others.

Rosenberg's staff delivered a letter to the clerk Thursday afternoon indicating that the senator, who has remained on as a rank-and-file member since relinquishing the presidency in December, planned to resign his seat effective 5 p.m. on Friday.

While investigators found that Rosenberg did not violate any Senate rules, members of the Ethics Committee decided that he has demonstrated a "significant failure of judgment and leadership" by not intervening despite his knowledge of Hefner racially and sexually harassing people that work in and around the Senate.

Investigators also faulted Rosenberg for violating Senate policy by insisting that Hefner has access to his computer so that his husband could review his schedule. The access to Rosenberg's accounts gave Hefner "unfettered" access to the Senate president's email and confidential information, and the report found that Hefner had abused that access and sent messages under Rosenberg's name.

Rosenberg's decision to resign came as an increasing number of Democratic senators began calling for his resignation. Seven Democrats were on the record publicly calling for Rosenberg to resign when his staff confirmed his intentions.

One of the final senators in that group was incoming Senate President Karen Spilka.

After saying Wednesday that she was committed to the "healing process" and restoring integrity to the Senate, Spilka on Thursday took it a step further and called for Rosenberg's resignation.

Spilka, who has claimed the support of her colleagues to succeed Senate President Harriette Chandler in July as the next Democratic leader of the Senate, said it is her obligation to protect the Senate, staff and public and the institution itself.

She was the highest ranking member of the Senate to call for Rosenberg to step down among a group that included Sens. Jamie Eldridge, James Welch, John Keenan, Paul Feeney and Barbara L'Italien. Gov. Charlie Baker and Attorney General Maura Healey, along with a number of House Republicans and statewide GOP candidates, had also said Rosenberg should step down. Senate Republicans did not call for his resignation before Rosenberg submitted his letter.

"Because Senator Rosenberg allowed a destructive pattern of behavior to continue over the course of many years, violating the trust that my colleagues and I invested in him, it is my firm belief that he should resign. Doing so will move us towards our goal of healing the Senate and making it a safe, welcoming and productive place for everyone," Spilka said.

Spilka's statement was released about an hour after Senate Democrats resumed their private deliberations over how to respond to the Senate Ethics Committee report, prepared by independent investigators with the law firm Hogan Lovells.

The six-member committee, which includes four Democrats and two Republicans, unanimously adopted the report and a recommendation that Rosenberg be barred from serving as Senate president, a member of leadership or as a committee chair through the 2019-2020 session, should he be re-elected in November.